Circuit breaker with interchangeable plug-in type trip unit sub-assembly

ABSTRACT

IN A CIRCUIT BREAKER OF THE SIZE AND TYPE INTENDED FOR HOME OR INDUSTRIAL USE, AN INTERCHANGEABLE PLUG-IN TRIP UNIT SUB-ASSEMBLY IS PROVIDED TO READILY PERMIT A VARIATION IN THE CIRCUIT BREAKER TRIPPING CHARACTERISTICS. IN THE DISCLOSED EMBODIMENTS THE REPLACEABLE TRIP UNIT SUBASSEMBLY CONSTITUTES A PORTION OF THE MAGNETICALLY ACTUATED TRIPPING MEANS. IN ONE EMBODIMENT, THE MAGNET AND ENERGIZING COIL IS REPLACEABLE AND IN ANOTHER EMBODIMENT THE ENTIRE ASSEMBLY INCLUDING THE ENERGIZING COIL, MAGNET, AND COOPERATING ARMATURE IS REPLACEABLE.

Jan. 26, "1 971 F. E. MYERS CIRCUIT BREAKER WITH INTERCHANGE'ABLEPLUG-IN TYPE TRIP UNIT SUB-ASSEMBLY 6; Sheets-Sheet -1 Filed April 2"11969 INVENTOR. FZ/J M14595 wvaen irs Jan. 26, 1971 1-; MYERS CIRCUITBREAKER WITH INTERCHANGEABLE PLUG TYPE TRIP UNIT SUB-ASSEMBLY FiledApril 21, 1969 6 Sheets-Sheet 2' wuw MYERS Jan. 26, 1971 CIRCUIT BREAKERWITH INTERCHANGEABLE PLUG TYPE TRIP UNIT SUB-ASSEMBLY 6 Sheets-Sheet s-7 Filed April 21, 1969 NNK MWK

" HF. E. MYERS cmcurr BREAKER WITH mmncuANGmBLr: PLUG-PIN TYPE 1313;UNITY sun-553mm, 1 v

riledg iili 1, 196 9 1 IYINVENI'ORL fZ/J 5 M aes Jan. 26, 1971 F, MYERS3,559,120 j CIRCUIT BREAKER WITH INTERCHANGEABLE PLUG-IN TYPE TRIP UNITSUB-ASSEMBLY I Filed April 21, 1969 6 Sheets-Sheet" 5- I I F s5 v .MN.

F. E. MYERS CIRCUIT BREAKER WITH INTERCHANGEABLE PLUG Jan. 26, 1971 TYPETRIP UNIT SUB-ASSEMBLY Filed April 21, 1969 6 Sheets-Sheet 6 M a .w M wW5 4 W [V 6 N a a bM i f v 4 r m: m y M W L f 6 F M w \\.w w m Thum V WII H Patented Jan. 26, 1971 3,559,120 CIRCUIT BREAKER WITHINTERCHANGEABLE PLUG-IN TYPE TRIP UNIT SUB-ASSEMBLY Felix E. Myers,Cherry Hill, N.J., assignor to I-T-E Imperial Corporation, Philadelphia,Pa., a corporation of Delaware Filed Apr. 21, 1969, Ser. No. 817,775Int. Cl. H01h 71/74 U.S. Cl. 335-42 6 Claims ABSTRACT OF THE DISCLOSUREIn a circuit breaker of the size and type intended for home orindustrial use, an interchangeable plug-in trip unit sub-assembly isprovided to readily permit a variation in the circuit breaker trippingcharacteristics. In the disclosed embodiments the replaceable trip unitsubassembly constitutes a portion of the magnetically actuated trippingmeans. In one embodiment, the magnet and energizing coil is replaceableand in another embodiment the entire assembly including the energizingcoil, magnet, and cooperating armature is replaceable.

My invention relates to circuit breakers and more particularly tocircuit breakers of the size and type intended for home or industrialuse.

Circuit breakers of the type to which my invention is particularlyapplicable are typically shown in my US. Patent No. 2,996,589 issuedAug. 15, 1961, entitled Pivoted Bimetal, and U.S. Patent applicationfiled in the name of Carl E. Gryctko, Ser. No. 647,999, June 22, 1967and now abandoned, both assigned to the I-T-E Circuit Breaker Company.It should, however, be understood that the reference to these presentlyavailable commercial circuit breaker constructions which may be modifiedto include my invention is not intended as a limitation of my invention,but the novel aspects of my arrangement may be practiced in conjunctionwith numerous other circuit breaker constructions of the type generallyintended for home or industrial use.

Such circuit breakers generally include a molded housing with recessesfor operatively locating and enclosing all the circuit breakercomponents. The circuit breaker components typically include at leastone pair of cooperating contacts, a latchable-operati-ng means forrapidly moving the contacts between their engaged and disengagedconditions responsive to predetermined fault conditions responsive topredetermined fault conditions, an overload responsive trip means forsensing the occurrence of the predetermined fault condition and a manualoperating means. The overload responsive trip means may typicallyinclude a magnetic trip, with the energizing current for the magnetbeing operatively proportional to the current flow through the circuitbreaker. When the current flow reaches a predetermined magnitude theforce of attraction between the magnet pole faces and its cooperatingarmature is sufficient to defeat the biasing force of the armature andthereby draw the armature towards the magnet. As the armature movestoward the magnet it engages the latch to thereby defeat the latchedengagement. Such circuit breakers may also, when desirable, include anoverload responsive bimetallic element. The bimetallic element is heatedby a current proportionally related to the current flow through thecircuit breaker. When a predetermined sustained overload conditionexists the bimetallic element will deflect sufliciently to defeat thelatch.

In the prior art circuit breakers of the type intended for such home orlight industrial use all the circuit breaker components, including thecomplete overload responsive trip means, are completely encased withinthe sealed housing. Thus, it has heretofore been necessary to constructand stock different overall circuit breaker units in accordance withvarious ratings of the circuit. That is, such circuit breakers aregenerally available in ratings such as 10, 15, 20, 20, 50 and amperes. Ihave recognized that the same circuit breaker construction may be usedfor different ratings merely by changing one or more of the componentsof the overload responsive trip means. For example, if a circuit breakeris constructed to safely withstand the current flow and interruptionassociated with a rating up to 50 amperes, the modification of suchcircuit breaker to have a 30, 20, 15 or 10 ampere rating may be achievedby merely changing the characteristic of the overload responsive tripmeans. Thus, my present invention would permit the manufacture, stockingand distribution of one basic circuit breaker frame for a wide varietyof ampere ratings. A plug-in subassembly would then be inserted toprovide the particular desired tripping characteristic.

The general idea of a replaceable trip unit assembly has heretofore beenavailable only with substantially larger frame circuit breakers, as forexample the type shown in U.S. Patent No. 3,319,195, issued May 5, 1967in the name of Albert Strobel and John C. Bromfield, and entitledCircuit Breaker Trip Unit Assembly. Such a separate trip unit assemblyis normally mounted upon the base of the substantially larger framecircuit breaker (as compared to the frame size of the presentinvention), and separate housing cover portions must then be bolted tothe base to enclose the trip unit assembly and the housing.

In accordance with my invention the housing advantageously includes apocket-type opening and the interchangeable sub-assembly includes wallsurfaces which are complementary with the housing wall surfaces aboutthe complementary opening for completely sealing the opening andenclosing the circuit breaker components. That is when theinterchangeable sub-assembly is located within the pocket-type openingof the circuit breaker, it serves to completely close the opening,thereby avoiding the need for any supplementary housing portions, astypically required in the larger frame circuit breakers which have aseparate base and cover portions.

In accordance with a further advantageous feature of the presentinvention, the overload responsive trip means includes an externallyaccessible calibration means for adjusting, within a predeterminedrange, the tripping characteristic established by the sub-assembly. Thisis illustratively shown as being accomplished by varying the initialarmature air gap separation. The latch bite may also be adjusted eitheralone or in conjunction with the armature air gap separation.

It is, therefore, seen that the present invention principally resides inproviding interchangeable trip unit characteristics in a circuit breakerof the size and type intended for a home or light industrial use.

It is, therefore, a principal object of the instant invention to providean improved circuit breaker having an interchangeable trip unit.

A further object of the present invention is to provide a circuitbreaker of the type intended for home or industrial use which includesan interchangeable trip means to permit a variation of the trippingcharacteristics.

Another object of the present invention is to provide a circuit breakerof the type intended for home or industrial use, which includes anexternally accessible pocket type opening for receiving a sub assemblywhich controls the tripping characteristics of the circuit breaker, withsaid sub-assembly also serving to seal the circuit breaker housingopening.

An additional object of the present invention is to provide a circuitbreaker of the type intended for home or industrial use in which themagnetic trip portion thereof includes a plug-in type of interchangeablesub-assembly for modifying the circuit breaker tripping characteristics.

These as well as other objects of the present invention will be readilyapparent from the following descriptions and drawings in which:

FIG. 1 is a cross-sectional view of a completely assembled circuitbreaker constructed in accordance with one embodiment of my invention.

FIG. 2 is an exploded perspective view of the circuit breaker housingand sub-assembly portions of the embodiment shown in FIG. 1, toillustrate the manner in which the sub-assembly is inserted within thecircuit breaker pocket-type opening.

FIG. 2A is a cross-sectional view along the line 2A-2A of FIG. 1.

FIGS. 3, 4 and 5 are plan, front and bottom views, respectively, of thecompletely assembled circuit breaker shown in FIGS. 1 and 2.

FIG. 6 shows the overload responsive trip means and latch portion of thecircuit breaker shown in FIG. 1, with a calibration adjustment havingbeen made of the armature air gap.

FIGS. 7, 8 and 9 are side, front and top views, respectively, of theself-contained sub-assembly portion utilized in conjunction with theembodiment of FIGS. 1 through 6.

FIG. 7A is a side view of a plug-in sub-assembly having a differenttripping characteristic.

FIG. 10 is a cross-sectional view of a circuit breaker constructed inaccordance with another embodiment of my invention.

FIG. 11 is an exploded perspective view showing the inter-relationshipof the circuit breaker housing and the self-contained sub-assembly ofthe FIG. 10 embodiment.

FIGS. 12, 13 and 14 are plan, front and bottom views, respectively, ofthe assembled circuit breaker in accordance with FIGS. 10 and 11.

FIGS. 15 and 16 are side and front views, respectively, of theself-contained sub-assembly utilized in conjunction with the embodimentsof FIGS. 10 through 14.

Referring initially to the embodiment of FIGS. 1 through 9, circuitbreaker 20 is of the general type shown in aforementioned US. patentapplication in that it includes a separate circuit breaker portion andcurrent limiting fuse. It should, however, be understood that the fuseportion may be deleted with the instant invention being applicable to adevice including only the circuit breaker portion, as shown inaforementioned US. Pat. 2,996,589. Likewise, the particular structuraldetails of the circuit breaker are merely for illustrative purposes andit should be readily appreciated that the present invention is adaptableto other circuit breaker constructions. Such circuit breakers maytypically have the following dimensions (referring to FIG. 2): a width Win the order of one inch; a depth D in the order of two inches; and anoverall length L in the order of three and a half inches. Should thecurrent limiting fuse portion be deleted, the overall length maygenerally be in the order of three inches. It should be understood thatthese dimensions are not given as critical limitations of the presentinvention, but merely represent a guide to understand the nature of thecompact circuit breaker to which the instant invention has demonstratedparticular utility.

Circuit breaker 20 is constructed within a molded housing including abase section 22 and complementary cover 24. The molded housing thusincludes a pair of opposed top and bottom walls 30, 3 2, respectively; apair of 0pposed first and second side walls 34, 36; and a pair ofopposed front and rear walls 38, 40. The housing sections are heldtogether by rivets 26. The internal volume bounded by the above notedwalls is separated into two compartments by a dividing region generallyshown by the dotted line 42. The first compartment 44 includes a circuitbreaker device generally constructed in accordance with aforementionedUS. Pat. No. 2,996,589 except for the pluggable trip unit assembly 150of the instant invention. The longitudinally adjacent second compartment46 contains a current limiting fuse 50 having characteristicsoperatively related to the circuit breaker device as is the subject ofaforementioned US patent application Ser. No. 647,999 and now abandoned.

The circuit breaker 20 includes a line terminal which is suitablyconnected to a source of electrical energy, e.g. the bus bar of a panelboard. Line terminal 100* is connected via electrical conductor portion101 to the stationary contact 102. Cooperating with stationary contact102 is a movable contact 104 connected to the lower end of a bifurcatedcontact arm 106. Parallel plate are extinguishing means 108 is providedin recesses 109. The upper end of the bifurcated contact arm abuts asuitable pivot formation of internally extending portion 112 of manualoperating member 114. Manual operating member 114 is pivoted about ahousing protrusion 113 which is entered into suitable recesses of themolded base 22 and cover 24. The manual operating member 114 includes anoutwardly extending portion 116 for manually moving the circuit breakerbetween its manual Off and manual On positions, as well as for resettingthe breaker after a trip operation, in the manner fully set forth inaforementioned US. Patent No. 2,996,589.

The contact carrying arm 106 has a braid member 120, with the oppositeend of the braid member being connected to internal contact finger 122.Another contact finger 127 is provided such that contact fingers 122 and124 will engage complementary elements 123, 125 of the sub-assemblyportion 150. Sub-assembly portion 150, as will be more fully discussed,includes an energizing coil 152 for the magnet for the magneticallyactuated circuit breaker fault responsive trip means. The current paththen continues through the coil 152 and contact 127 to conductor 132which has a tulip-type clip portion 133, for engaging the upper ferruleterminal 134 of the fuse 50. The lower ferrule terminal 136 of the fuseis in turn connected to tulip-type terminal 138, which is connected viaconductor portion 139 to the externally accessible load terminal 140.

The operating mechanism for bringing about the engagement anddisengagement of the cooperating contacts 102, 104 comprises a latchablecradle member 141 which is pivotally mounted at one end thereof to baseprotrusion 142. Cradle 141 also carries a kicker 145 which gives contactarm 106 a hammer-like blow during the tripping operation to ensureseparation of the circuit breaker contacts.

One end of an operating spring 148 is connected to cradle 141 ataperture 150, while the other end of the operating spring is connectedto contact arm 106 at aperture 152. Operating spring 148 is always intension, thereby urging contact arm end 115 upwardly into engagementwith its pivotal mounting to manual operating member 114, and latchablecradle member 141 clockwise about its pivotal mounting 142. The force ofoperating spring 148, relative to the pivotal mounting of contact arm106, also serves to urge the movable contact 104 into firm engagementwith its cooperating stationary contact 102 to provide the necessarycontact engagement forces.

Latchable cradle 141 includes a latchable tip 144 which seats upon Iatchportion 154 carried by the lower end of an elongated latching member124. A bearing pin 156 is suitably secured to an intermediate region ofelongated latching member 124, as by welding, and enters suitablecircular recesses of the circuit breaker base 22 and cover 24 forpivotally mounting the latching member 124. The latching member 124 isbiased in a clockwise direction about its pivot 156 by spring 158.Calibrated adjustment of the trip unit, with the insertion of aparticular plug-in sub-assembly 150, is obtained by calibrating screw160 which bears against intermediate connecting member 162 to modify thelatch bite.

If desired, the latching member 124 may be formed of a bimetallicelement, and suitably heated in a manner proportionally related to thecurrent flow through the circuit breaker, as shown in aforementioned US.patent application 647,999 and now abandoned.

As discussed in aforementioned US. patent application Ser. No. 647,999and now abandoned the fuse member 50 is retained within a rotatable fuseholder 210, which has a cam surface 212 along the underside thereof. Camsurface 212 cooperates with interlock trip lever 215, and its associatedbiasing means 217, to permit counterclockwise movement about its pivot219, in the event of fuse removal, such that end 221 thereof engages thelatching lever 124, for tripping the circuit breaker upon such fuseremoval.

In accordance with the instant invention, the overload responsive tripmeans includes a plug-in type and selfcontained sub-assembly 150. Thissub-assembly is shown provided in conjunction with the magneticallyactuated trip means. Sub-assembly 150 includes a magnet comprising amagnet bottom plate 160, top plate 162, magnet in 164, and mountingblock 168. The energizing coil 152 is located about the pin 164 betweenthe upper and lower plates 160, 162. The ends of the coil are connectedto finger type terminals 123, 125 located by insulative means 121.Terminals 123, 125 make contact with internally located conductors 122,127 within the pocket-type opening 200.

The magnetic assembly located within sub-assembly 150 therefore includesopposed pole faces 161, 163. These operate in conjunction with armaturemember 170, pivotally mounted within the circuit breaker housing at 171and biased by spring 173. When the armature member 170 is drawn towardsthe cooperating pole faces 161, 162 of the magnet, the extension 175thereof will engage the lower region of the latching member 124, tothereby defeat the latching engagement between cradle tip 144 andlatching ledge 154.

In accordance with an extremely advantageous feature of my invention,the initial air gap separation between armature 170 and pole faces 161,163 may be calibrated by externally accessible button member 180. Buttonmember 180 is rotated within recess 182 of the circuit breaker top wall30, and is rotatable about axis 181, as by a screwdriver insertable inslot 183. Button 180 is maintained in its position by spring member 184which abuts shoulder portion 185 thereof. An internal eccentric opening187 is provided in button member 180, having the configuration shown inFIG. 2A.

The calibration adjustment further includes an intermediate connectinglever 190, pivotally mounted about 192. Member 190 is biasedcounterclockwise about pivot 192 by spring member 195, mounted onhearing 156. The extent of clockwise movement of the intermediatecalibration member 190 is limited by its engagement with upstanding wall188 of the eccentric calibration opening 187. End 195 of calibrationlever 140 abuts the rear of the armature 170, and thereby limits itscounterclockwise movement about pivot 171, under the influence ofbiasing means 173. Hence, it should be recognized that the permissiblemovement of calibration member 190, as controlled by the position ofexternally accessible adjustment 180, provides a variation of theinitial air gap between the extremes shown in FIGS. 1 and 6. That is,FIG. 1 corresponds to the High setting of the circuit breaker. Themaximum armature air gap separation requires the maximum energization tocause attraction of armature 170 to the cooperating pole faces 161, 163.Conversely, with a minimum air gap separation as shown in FIG. 6, thereluctance of the magnetic circuit is significantly decreased, therebyrequiring lesser magnetization current in order to attract armature 170to the magnet.

The lower housing wall 32 includes a pocket-type opening 200, for thereception of the sub-assembly 150. Subassembly 150 is of such aconfiguration that when it is properly inserted (such that contactfingers 123, are in electrical contact with interior located contactelements 122, 127) the housing will be completely enclosed, as shown inFIGS. 3-5. It should be readily recognized that by substituting anothersub-assembly (FIG. 7A) having a different energizing coil characteristic(e.g. substantially lesser turns), the rating of the circuit breakerwill be increased. Hence, it is seen that the present invention readilypermits a change in the circuit breaker rating by merely removing onesub-assembly 150 of the trip unit and inserting another sub-assembly150', having the same dimensional configuration, but differentelectrical characteristics.

Reference is now made to FIGS. 10 through 16, which show anotherembodiment 20' of circuit breaker constructed in accordance with myinvention. The circuit breaker 20' differs from circuit breaker 20 ofthe FIGS. l-9 embodiment, principally in that the sub-assembly 250includes the entire magnetically responsive trip means and calibration,instead of containing only the magnet portion thereof. Those portions ofcircuit breaker 20' which are identical with circuit breaker 20 aresimilarly numbered. Thus, it should be noted that the fuse compartment46 is unchanged, as well as the basic circuit breaker operatingmechanism including cradle member 141, spring 148, operating handle 114and cooperating contact pairs 22, 24.

The latching member 124 is pivotally mounted at bearing 156 andsimilarly includes a latching ledge 154 which engages the cradle tip144. The interlock for effecting tripping of the circuit breaker uponthe removal of fuse holder 210 is now obtained by interlock lever 225,which is pivoted at 156. Interlock lever 225 includes a cam followerportion 227 at one end thereof, which is moved by cam surface 212 of thefuse holder, against the bias of spring 229. Upon removal of fuse holder210, the lever 225 rotates counterclockwise about pivot 156 moving theend 231 into engagement with the upper end of the latching member 124,to effect counterclockwise movement of 124 about 156 and defeat of thelatching engagement between cradle tip 144 and latching ledge 141.

The sub-assembly 250 includes the entire magnetically responsive tripmeans, as well as the calibration adjustment thereof. Mounting base 252thereof is of a configuration, such that when it is located within thecircuit breaker pocket opening 251, it completely seals the side andbottom walls of the opening 251, so as to enclose the circuit breaker. AU-clip 254 is located within grooves 255 of the mounting bases 252.Grooves 255 are in registry with grooves 257 of the circuit breakerfront and rear walls, such that U-shaped member 254, when moved intogroove 257 (see FIGS. 13 and 14) serves to maintain the sub-assembly 250within the housing opening. The body region 253 of the U-shaped clip,when inserted, sits in groove 259 across the bottom wall of the circuitbreaker housing.

The sub-assembly 250 includes a magnet portion having upper magnetmember 260, lower magnet member 261, interconnecting member 262, andenergizing coil 264. Pivotally mounted in suitable recesses 266, withinthe lower magnet member is the armature member 270, biased away from themagnet pole faces by U-shaped spring member 282. The electricalinterconnection of the subassembly coil 264 with the circuit breakercurrent path is obtained by contact elements 272, 274, which engagecooperating contact elements 273, 275, respectively, within the circuitbreaker opening.

The initial air gap calibration of the magnetically actuated overloadresponsive trip means is obtained by wheel-like calibration member 290,which extends through housing opening 293. Wheel 290 includes a cammingsurface 291, which engages cam follower portion 293 of the calibrationlever 294. Calibration lever 294 is pivotally mounted at pin 296 andbiased counterclockwise by spring member 298. The opposite end 295 ofthe lever 294 engages inwardly turned ear portion 271 of the armature,thereby providing a range of adjustment shown between the dottedconditions of FIG. 16.

It should now be readily apparent that the insertion of the entiresub-assembly 250 modifies the entire tripping characteristics of thecircuit breaker, with the entire magnetically actuated overload tripmeans as well as its external calibration being mounted as aself-contained subassembly 250.

Although there has been described preferred embodiments of this novelinvention, many variations and modifications will now be apparent tothose skilled in the art. Therefore, this invention is to be limited,not by the specific disclosure herein, but only by the appending claims.

What is claimed is:

1. A circuit breaker of the type intended for home or industrial usecomprising:

a housing for operatively locating and enclosing the circuit breakercomponents, said components in cluding:

at least one pair of cooperating contacts;

an operating means for moving said contacts between their engaged anddisengaged conditions, responsive to at least one type of predeterminedfault condition;

an overload responsive trip means for sensing the occurrence of saidpredetermined fault condition and initiating movement of said operatingmeans to the contact disengaged TRIP condition, said overload responsivetrip means including magnetically actuated means having magnet, armatureand energizing coil elements operatively responsive to the current flowthrough said circuit breaker;

the improvement comprising:

said overload responsive trip means including at least a portionconstructed as an integral self-contained plug-in type sub-assembly;

said circuit breaker housing including an externally accessible pockettype opening for receiving said sub-assembly;

means for electrically and mechanically interconnecting saidsub-assembly to the remaining circuit breaker parts internal of saidhousing in a manner per- 8 mitting ready removal of said sub-assemblyfor replacement by another sub-assembly;

said sub-assembly including at least one of the elements of saidmagnetically actuated means for establishing the trip characteristics ofsaid overload responsive means, such that replacement of thesub-assemblzy alters the circuit breaker trip rating;

said sub-assembly including wall surfaces complementary with saidhousing wall surfaces about said opening for completely sealing saidopening and enclosing the circuit breaker components.

2. In a circuit breaker of the type set forth in claim 1,

further including externally accessible calibration means for adjustingthe initial air gap separation between the pole faces of said magnetelement and said armature element to vary the trip characteristicsestablished by said subassembly about a predetermined range.

3. In a circuit breaker of the type set forth in claim 1,

said sub-assembly including said energizing coil element such that thetrip rating of said circuit breaker varies as different sub-assembliesof differing energizing coil characteristics are substituted as part ofsaid overload responsive trip means.

4. In a circuit breaker of the type set forth in claim 1,

said sub-assembly including all of said magnet, armature and energizingcoil elements.

5. In a circuit breaker of the type described in claim 1,

said circuit breaker housing having a width in the order of one inch.

6. In a circuit breaker of the type described in claim 1,

said circuit breaker housing having a Width in the order of one inch,and a depth in the order of 2 /2 inches.

References Cited UNITED STATES PATENTS 2,982,834 5/1961 Edmunds 337 713,354,277 11/1967 Stanback 337 210 HAROLD BROOME, Primary Examiner U.S.Cl. X.R. 335-176

